Allow creating fixed-size window surfaces.

extensions/EGL_ANGLE_window_fixed_size.txt

+Name
+
+    ANGLE_window_fixed_size
+
+Name Strings
+
+    EGL_ANGLE_window_fixed_size
+
+Contributors
+
+    John Bauman
+    Shannon Woods
+
+Contacts
+
+    John Bauman, Google Inc. (jbauman 'at' google.com)
+
+Status
+
+    Complete
+
+Version
+
+    Version 4, February 24, 2014
+
+Number
+
+    EGL Extension #??
+
+Dependencies
+
+    This extension is written against the wording of the EGL 1.4
+    Specification.
+
+Overview
+
+    This extension allows creating a window surface with a fixed size that is
+    specified when it is created.
+
+New Types
+
+    None
+
+New Procedures and Functions
+
+    None
+
+New Tokens
+
+    Accepted by the <attribute> parameter of eglQuerySurface and by the
+    <attrib_list> parameter of eglCreateWindowSurface:
+
+    EGL_FIXED_SIZE_ANGLE        0x3201
+
+Additions to Chapter 3 of the EGL 1.4 Specification:
+
+    Modify the third paragraph of Section 3.5.1 (Creating On-Screen Rendering Surfaces)
+
+    "<attrib_list> specifies a list of attributes for the window. The list has
+    the same structure as described for eglChooseConfig.  Attributes that can
+    be specified in <attrib_list> include EGL_RENDER_BUFFER,
+    EGL_VG_COLORSPACE, EGL_VG_ALPHA_FORMAT, EGL_FIXED_SIZE_ANGLE, EGL_WIDTH,
+    and EGL_HEIGHT."
+
+    Add before the last paragraph of Section 3.5.1
+
+    "EGL_FIXED_SIZE_ANGLE specifies whether the surface must be resized by the
+    implementation when the native window is resized.  The default value is
+    EGL_FALSE.  Its value can be EGL_TRUE, in which case the size must be
+    specified when the window is created, or EGL_FALSE, in which case the size
+    is taken from the native window. Its default value is EGL_FALSE.
+
+    If the value of EGL_FIXED_SIZE_ANGLE is EGL_TRUE, the window surface's
+    size in pixels is specified by the EGL_WIDTH and EGL_HEIGHT attributes,
+    and will not change throughout the lifetime of the surface. If its value
+    is EGL_FALSE, then the values of EGL_WIDTH and EGL_HEIGHT are ignored and
+    the window surface must be resized by the implementation subsequent to the
+    native window being resized, and prior to copying its contents to the
+    native window (e.g. in eglSwapBuffers, as described in section 3.9.1.1).
+    The default values for EGL_WIDTH and EGL_HEIGHT are zero. If the value
+    specified for either of EGL_WIDTH or EGL_HEIGHT is less than zero then an
+    EGL_BAD_PARAMETER error is generated."
+
+    Add the following entry to Table 3.5
+    (Queryable surface attributes and types)
+
+    Attribute            Type    Description
+    -------------------- ------- ---------------------------------------------
+    EGL_FIXED_SIZE_ANGLE boolean Surface will not be resized with a native
+                                 window
+
+    Replace the last paragraph on page 37 in Section 3.5.6 (Surface Attributes)
+
+    "Querying EGL_WIDTH and EGL_HEIGHT returns respectively the width and
+    height, in pixels, of the surface. For a pixmap surface or window surface
+    with EGL_FIXED_SIZE_ANGLE set to EGL_FALSE, these values are initially
+    equal to the width and height of the native window or pixmap with respect
+    to which the surface was created. If the native window is resized and the
+    corresponding window surface is not fixed size, the corresponding window
+    surface will eventually be resized by the implementation to match (as
+    discussed in section 3.9.1). If there is a discrepancy because EGL has not
+    yet resized the window surface, the size returned by eglQuerySurface will
+    always be that of the EGL surface, not the corresponding native window."
+
+    Add the following paragraph to Section 3.5.6 (Surface Attributes)
+
+    "Querying EGL_FIXED_SIZE_ANGLE returns EGL_FALSE if the surface will be
+    resized to match a native window, and EGL_TRUE if the surface cannot be
+    resized."
+
+    Alter the beginning of the first paragraph of Section 3.9.1.1 (Native
+    Window Resizing)
+
+    "If <surface> does not have EGL_FIXED_SIZE_ANGLE set and the native window
+    corresponding to <surface> has been resized prior to the swap, <surface>
+    must be resized to match."
+
+Issues
+
+    1. Should there be a way to resize a window surface that had its size
+    specified initially.
+
+    RESOLVED: No. Surfaces that have their sizes specified initially must have
+    EGL_FIXED_SIZE_ANGLE set and can never be resized.
+
+Revision History
+
+    Version 4, 2014/02/24 - formatting changes.
+
+    Version 3, 2014/02/12 - ignore EGL_WIDTH and EGL_HEIGHT if
+    EGL_FIXED_SIZE_ANGLE is EGL_FALSE
+
+    Version 2, 2014/02/07 - rename to EGL_ANGLE_window_fixed_size, and add an
+    EGL_FIXED_SIZE_ANGLE token.
+
+    Version 1, 2014/02/05 - first draft.

include/EGL/eglext.h

@@ -347,6 +347,11 @@ typedef EGLuint64NV (EGLAPIENTRYP PFNEGLGETSYSTEMTIMENVPROC) (void);
 #define EGL_LOSE_CONTEXT_ON_RESET_EXT		0x31BF
 #endif
 
+#ifndef EGL_ANGLE_window_fixed_size
+#define EGL_ANGLE_window_fixed_size 1
+#define EGL_FIXED_SIZE_ANGLE	0x3201
+#endif
+
 #ifdef __cplusplus
 }
 #endif

src/libEGL/Display.cpp

@@ -191,6 +191,10 @@ EGLSurface Display::createWindowSurface(HWND window, EGLConfig config, const EGL
     const Config *configuration = mConfigSet.get(config);
     EGLint postSubBufferSupported = EGL_FALSE;
 
+    EGLint width = 0;
+    EGLint height = 0;
+    EGLint fixedSize = EGL_FALSE;
+
     if (attribList)
     {
         while (*attribList != EGL_NONE)
@@ -211,6 +215,15 @@ EGLSurface Display::createWindowSurface(HWND window, EGLConfig config, const EGL
               case EGL_POST_SUB_BUFFER_SUPPORTED_NV:
                 postSubBufferSupported = attribList[1];
                 break;
+              case EGL_WIDTH:
+                width = attribList[1];
+                break;
+              case EGL_HEIGHT:
+                height = attribList[1];
+                break;
+              case EGL_FIXED_SIZE_ANGLE:
+                fixedSize = attribList[1];
+                break;
               case EGL_VG_COLORSPACE:
                 return error(EGL_BAD_MATCH, EGL_NO_SURFACE);
               case EGL_VG_ALPHA_FORMAT:
@@ -223,6 +236,17 @@ EGLSurface Display::createWindowSurface(HWND window, EGLConfig config, const EGL
         }
     }
 
+    if (width < 0 || height < 0)
+    {
+        return error(EGL_BAD_PARAMETER, EGL_NO_SURFACE);
+    }
+
+    if (!fixedSize)
+    {
+        width = -1;
+        height = -1;
+    }
+
     if (hasExistingWindowSurface(window))
     {
         return error(EGL_BAD_ALLOC, EGL_NO_SURFACE);
@@ -234,7 +258,7 @@ EGLSurface Display::createWindowSurface(HWND window, EGLConfig config, const EGL
             return EGL_NO_SURFACE;
     }
 
-    Surface *surface = new Surface(this, configuration, window, postSubBufferSupported);
+    Surface *surface = new Surface(this, configuration, window, fixedSize, width, height, postSubBufferSupported);
 
     if (!surface->initialize())
     {
@@ -487,6 +511,8 @@ void Display::initExtensionString()
 
     mExtensionString += "EGL_ANGLE_query_surface_pointer ";
 
+    mExtensionString += "EGL_ANGLE_window_fixed_size ";
+
     if (swiftShader)
     {
         mExtensionString += "EGL_ANGLE_software_display ";

src/libEGL/Surface.cpp

@@ -25,7 +25,7 @@
 namespace egl
 {
 
-Surface::Surface(Display *display, const Config *config, HWND window, EGLint postSubBufferSupported) 
+Surface::Surface(Display *display, const Config *config, HWND window, EGLint fixedSize, EGLint width, EGLint height, EGLint postSubBufferSupported) 
     : mDisplay(display), mConfig(config), mWindow(window), mPostSubBufferSupported(postSubBufferSupported)
 {
     mRenderer = mDisplay->getRenderer();
@@ -39,9 +39,10 @@ Surface::Surface(Display *display, const Config *config, HWND window, EGLint pos
     mRenderBuffer = EGL_BACK_BUFFER;
     mSwapBehavior = EGL_BUFFER_PRESERVED;
     mSwapInterval = -1;
-    mWidth = -1;
-    mHeight = -1;
+    mWidth = width;
+    mHeight = height;
     setSwapInterval(1);
+    mFixedSize = fixedSize;
 
     subclassWindow();
 }
@@ -61,6 +62,8 @@ Surface::Surface(Display *display, const Config *config, HANDLE shareHandle, EGL
     mSwapBehavior = EGL_BUFFER_PRESERVED;
     mSwapInterval = -1;
     setSwapInterval(1);
+    // This constructor is for offscreen surfaces, which are always fixed-size.
+    mFixedSize = EGL_TRUE;
 }
 
 Surface::~Surface()
@@ -96,7 +99,7 @@ bool Surface::resetSwapChain()
     int width;
     int height;
 
-    if (mWindow)
+    if (!mFixedSize)
     {
         RECT windowRect;
         if (!GetClientRect(getWindowHandle(), &windowRect))
@@ -140,7 +143,7 @@ bool Surface::resizeSwapChain(int backbufferWidth, int backbufferHeight)
     ASSERT(backbufferWidth >= 0 && backbufferHeight >= 0);
     ASSERT(mSwapChain);
 
-    EGLint status = mSwapChain->resize(backbufferWidth, backbufferHeight);
+    EGLint status = mSwapChain->resize(std::max(1, backbufferWidth), std::max(1, backbufferHeight));
 
     if (status == EGL_CONTEXT_LOST)
     {
@@ -163,7 +166,7 @@ bool Surface::resetSwapChain(int backbufferWidth, int backbufferHeight)
     ASSERT(backbufferWidth >= 0 && backbufferHeight >= 0);
     ASSERT(mSwapChain);
 
-    EGLint status = mSwapChain->reset(backbufferWidth, backbufferHeight, mSwapInterval);
+    EGLint status = mSwapChain->reset(std::max(1, backbufferWidth), std::max(1, backbufferHeight), mSwapInterval);
 
     if (status == EGL_CONTEXT_LOST)
     {
@@ -300,22 +303,23 @@ void Surface::unsubclassWindow()
 bool Surface::checkForOutOfDateSwapChain()
 {
     RECT client;
-    if (!GetClientRect(getWindowHandle(), &client))
-    {
-        ASSERT(false);
-        return false;
-    }
-
-    // Grow the buffer now, if the window has grown. We need to grow now to avoid losing information.
-    int clientWidth = client.right - client.left;
-    int clientHeight = client.bottom - client.top;
-    bool sizeDirty = clientWidth != getWidth() || clientHeight != getHeight();
-
-    if (IsIconic(getWindowHandle()))
+    int clientWidth = getWidth();
+    int clientHeight = getHeight();
+    bool sizeDirty = false;
+    if (!mFixedSize && !IsIconic(getWindowHandle()))
     {
         // The window is automatically resized to 150x22 when it's minimized, but the swapchain shouldn't be resized
         // because that's not a useful size to render to.
-        sizeDirty = false;
+        if (!GetClientRect(getWindowHandle(), &client))
+        {
+            ASSERT(false);
+            return false;
+        }
+
+        // Grow the buffer now, if the window has grown. We need to grow now to avoid losing information.
+        clientWidth = client.right - client.left;
+        clientHeight = client.bottom - client.top;
+        sizeDirty = clientWidth != getWidth() || clientHeight != getHeight();
     }
 
     bool wasDirty = (mSwapIntervalDirty || sizeDirty);
@@ -412,6 +416,11 @@ gl::Texture2D *Surface::getBoundTexture() const
     return mTexture;
 }
 
+EGLint Surface::isFixedSize() const
+{
+    return mFixedSize;
+}
+
 EGLenum Surface::getFormat() const
 {
     return mConfig->mRenderTargetFormat;

src/libEGL/Surface.h

@@ -34,7 +34,7 @@ class Config;
 class Surface
 {
   public:
-    Surface(Display *display, const egl::Config *config, HWND window, EGLint postSubBufferSupported);
+    Surface(Display *display, const egl::Config *config, HWND window, EGLint fixedSize, EGLint width, EGLint height, EGLint postSubBufferSupported);
     Surface(Display *display, const egl::Config *config, HANDLE shareHandle, EGLint width, EGLint height, EGLenum textureFormat, EGLenum textureTarget);
 
     ~Surface();
@@ -64,6 +64,8 @@ class Surface
     virtual void setBoundTexture(gl::Texture2D *texture);
     virtual gl::Texture2D *getBoundTexture() const;
 
+    EGLint isFixedSize() const;
+
 private:
     DISALLOW_COPY_AND_ASSIGN(Surface);
 
@@ -99,6 +101,7 @@ private:
 //  EGLenum vgColorSpace;          // Color space for OpenVG
     EGLint mSwapInterval;
     EGLint mPostSubBufferSupported;
+    EGLint mFixedSize;
     
     bool mSwapIntervalDirty;
     gl::Texture2D *mTexture;

src/libEGL/libEGL.cpp

@@ -471,6 +471,9 @@ EGLBoolean __stdcall eglQuerySurface(EGLDisplay dpy, EGLSurface surface, EGLint
           case EGL_POST_SUB_BUFFER_SUPPORTED_NV:
             *value = eglSurface->isPostSubBufferSupported();
             break;
+          case EGL_FIXED_SIZE_ANGLE:
+            *value = eglSurface->isFixedSize();
+            break;
           default:
             return egl::error(EGL_BAD_ATTRIBUTE, EGL_FALSE);
         }